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951.
In the Ilmenogorsk metamorphic complex, Southern Urals, the Archean gneissic core and Riphean-Vendian quartzite-schist framing are traditionally distinguished. The age of the latter is not reliably determined. There were speculations about its possible Paleozoic age. Those are partially confirmed by isotopic data. The quartzite in the upper part of the section of schist strata detrital mineral grains were found, and they are similar to accessory minerals of the Kisegach Massif granitoids occurring among quartzite. The granitoids demonstrated to form phases of various age. It is assumed that the oldest of them (predating folding) could be intruded synchronously with sedimentation and serve as porvenance for the quartzite. The most informative of these minerals is monazite. Microprobe analyses results on monazite from quartzite and granite are given. Their REE distribution is demonstrated to be similar. This confirms the possibility of the granitoid erosion at the time of quartz sandstone deposition. Since the K-Ar age of granitoids Kisegach Massif is 252 ± 8 Ma, it was concluded that the Kyshtym quartzite-schist unit of Ilmeny has about the same age. 相似文献
952.
The testing and development of topological approaches to the analysis of solar magnetic fields are considered. A technique based on the geometry of random fields, mathematical morphology and topology, and scale-space analyses are applied to describe and diagnose the pre-flare dynamics of the magnetic fields of solar active regions using HMI/SDO magnetograms. The results show that this formalism can be used to diagnose pre-flare dynamics over time intervals that are of practical interest. 相似文献
953.
在山东省莒南地质公园内发现6个小型恐龙足迹化石,被归入足迹属Minisauripus。化石产于下白垩统大盛群田家楼组,时代为早白垩世巴列姆(Barremian)—阿普特期(Aptian)。5个较大,长约6cm,产于下部“主”层面上,其中4个组成2节行迹;1个较小,长约3cm,位于“主”层面30cm之上的上部层面上。山东Minisauripus的特征是:足迹个体小(长3.1~5.6cm,宽2.0~3.7cm),三趾型,略不对称;足迹纵长,各趾近平行,趾垫较清晰;趾末端较钝,但爪迹较尖。Ⅲ趾比Ⅳ趾略长,而Ⅳ趾比Ⅱ趾略长且窄。此外,步幅较长,足长与步长之比约为10∶1。与四川、韩国的Minisauripus不同之处是:足迹个体较大,长约是它们的2倍。继中国四川和韩国之后,山东是Minisauripus在全球的第三个发现点。 相似文献
954.
影响事件层保存潜力的主要因素有 :纯粹的沉积速率、生物成因的混合速率以及机械改造的规模,可以从时间规模 (过渡时间和消除时间 )的角度来考虑事件层保存潜力。基底的机械改造同样对于事件层和正常天气下的沉积物的保存具有重要影响。综合分析影响事件层保存潜力的各种因素表明,在近基的临滨带中、上部及滨外带下部,事件层具有较高的保存潜力,而在近基及远基两端之间的临滨带下部及滨外带上部,事件层保存潜力较低. 相似文献
955.
以位于三峡库区的龙门河森林自然保护区为研究区,综合利用线性光谱混合模型和几何光学模型,基于高光谱遥感数据提取森林结构参数是本文研究的重点。在研究区地面调查数据的基础上,通过高光谱数据和混合光谱分解法,获得反演几何光学模型所需的四分量参数,根据背景光照分量与森林植被冠层各参数间的关系,反演得到森林冠层郁闭度及平均冠幅的定量分布图,并利用37个野外实测样本进行结果验证。 相似文献
956.
In multi-functional mountainous landscapes worldwide, conservation of natural values is a major task. Here, pro-active policies can be a way forward. National Environmental Quality Objectives (EQO) to solve environmental problems for future generations, however, often wrestle with being too visionary and lacking specificity, which complicates their implementation. The EQO 相似文献
957.
ZHOU Ming-jun ZHOU Gordon G. D. CUI Kahlil Fredrick E. SONG Dong-ri LU Xue-qiang 《山地科学学报》2019,30(4):778-792
Accurate prediction of the hydrographs of outburst floods induced by landslide dam overtopping failure is necessary for hazard prevention and mitigation. In this study, flume model tests on the breaching of landslide dams were conducted. Unconsolidated soil materials with wide grain size distributions were used to construct the dam. The effects of different upstream inflow discharges and downstream bed soil erosion on the outburst peak discharge were investigated. Experimental results reveal that the whole hydrodynamic process of landslide dam breaching can be divided into three stages as defined by clear inflection points and peak discharges. The larger the inflow discharge, the shorter the time it takes to reach the peak discharge, and the larger the outburst flood peak discharge. The scale of the outburst floods was found to be amplified by the presence of an erodible bed located downstream of the landslide dam. This amplification decreases with the increase of upstream inflow. In addition, the results show that the existence of an erodible bed increases the density of the outburst flow, increasing its probability of transforming from a sediment flow to a debris flow. 相似文献
958.
959.
Emilio Donoso Ana O'Mill Diego G. Lambas 《Monthly notices of the Royal Astronomical Society》2006,369(1):479-484
We analyse a high-redshift sample (0.4 < z < 0.5) of luminous red galaxies (LRGs) extracted from the Sloan Digital Sky Survey data release 4 and their surrounding structures to explore the presence of alignment effects of these bright galaxies with neighbour objects. In order to avoid projection effects, we compute photometric redshifts for galaxies within 3 h −1 Mpc in projection of LRGs and calculate the relative angle between the LRG major axis and the direction to neighbours within 1000 km s−1 . We find a clear signal of alignment between LRG orientations and the distribution of galaxies within 1.5 h −1 Mpc. The alignment effects are present only for the red population of tracers; LRG orientation is uncorrelated to the blue population of neighbour galaxies. These results add evidence to the alignment effects between primaries and satellites detected at low redshifts. We conclude that such alignments were already present at z ∼ 0.5. 相似文献
960.
S. Caquard G. Brauen B. Wright P. Jasen 《International journal of geographical information science》2013,27(11-12):1219-1245
In this paper we draw on the analysis of sound in film theory in order to explore the potential that sound offers cybercartography. We first argue that the theoretical body developed in film studies is highly relevant to the study of sound/image relationships in mapmaking. We then build on this argument to develop experimental animated and interactive sound maps for the Cybercartographic Atlas of Antarctica that further explore the potential of sound for integrating emotional, cultural and political dimensions in cartography. These maps have been designed to recreate cinematic soundscapes, to provide contrapuntal perspectives on the cartographic image and to generate an aural identity of the atlas. As part of this experimental mapping, an innovative sound infrastructure is being developed to allow complex sound designs to be transmitted over the Internet as part of atlas content. Through this infrastructure the user can select as well as contribute his own sounds. The overall cartographic message is becoming less predictable, thus opening new perspectives on the way we design, interact with, and modify sounded maps over the Internet. 相似文献